Method of increasing the usefulness of solid isomerization catalyst masses



July 15, 1947- N.-F. MYERS 2,423,845

METHOD OF INCREASING THE USEFULNESS 0F SOLID ISOHERIZATION CATALYST MASSBS- Filed uarcn 21, 1942 QM .Tm

WQ, `ma 355 N ir mw .nm

raceteam, 15, 1947 'y l 2,423,845

UNITED s'rA'ras PATENT ori-"ica *a J .fr i umzug 'i alarmas *t F SOLID ISOMERIZATION CATALYST .v MASSES Nemi r. um. short um., n.1.. am u Standard Oil Development Company, a oorporation of Delaware Application Marea zi, ma, serial No. am

^ l '30 Claims. (Cl. 26o-683.5) 2' i This application is a continuation in part of cointo highly absorbent carrier substances to be Vpending application U. S. Serial No. 422.820. med p more fully hereinafter described. In preparing December 13, 194,1, by Norval F. Myers'. v these catalysts masses it has been found desir- The present invention relates to the isomerizaable, and in fact essential, to a smooth and ecotion of paramnic hydrocarbons, in particular nomical operation' obviating the necessity for frestraight chain or normal paraflinic hydrocarquent plant shutdowns, to impregnate or sorb bons containing at least four carbon atoms per on or in the carrier substance only suillcient alumolecule, in particular normal butane and nori minllm-chloride 88 will be telleeiellely held in the lmai pentane. to produce the corresponding .pores of the carrier substance under the condibranched chain or iso paramns catalytically by A tions of isomerization obtaining. This is expedivmeans of Friedel-Crafts type catalysts, in x'n'ir-` ent by reason of the fact that aluminum chloride tlcular the aluminum haiides such as aluminum vapors vwhen present to any great extent in the chloride, while carrying out the reaction under reacted eiliuent from the isomerization reactor isomerization reaction conditions and in the prestend to condense and deposit in nivel. Pipes, stills `ence ofpromotlonalamountsof halogen-containand the like. necessitating the removal and shuting compounds. l down for cleaning of these various pieces of In the isomerization of normal paraillns of at equipment. Althoush it is preferred to make up least four carbon atoms per molecule to their corthe catalyst mass so that only tenaciously held responding branched chain isomers, it is cusaluminum chloride is present in the pores of the tomary to employ catalysts of the Friedel-Crafts carrier, the invention is not restricted to the use type such as, for examp1ezinc chloride, aluminum of this particular type of catalyst mass but is chloride, aluminum bromide, iron chloride and likewise aplllieeble tothe ease Where' aluminum .the like, in conjunction with promoters such as, chloride is present in excess of the amount re- .for example, chlorine, bromine, hydrogen chloquired tobe only tenaciouslyheld in the pores ride, hydrogen bromide, carbon tetrachloride, 2s of the carrier. in which case provision is made chloroform, the lower alkyl halides such as, for 5 for the removal ofthe excess aluminum chloride lexample, methyl, ethyl, propyl, butyl chlorides VePOrS by their sorption in another mass of the and bromides and the like. lSmall amounts of carrier or the like.l By the use of the expression kwater have also been employed for promoting this tenaciously held or equivalent expressions as reaction. The process has heretofore been carv used in the description and appended claims, it ried out-chiefly in the liquid phase.` In the case is intended to cover a catalystmass comprising of normal butane, under the temperatures ordia Porous carrier and aluminum' chloride in which narily employed, some superatmospheric presthe aluminum chloride is sorbed in and on the sure is necessary to maintain the liquid phase said porous carrier only to such an extent that.

- "operation, while mthecase cf ncrma1 pentane appreciable amounts of aluminum chloride. will pressure may or may not heV used as desired. notberemoved from the catalyst mass uponus'ing However, the diiliculties encountered in liquid the same in the 'lsomerization process hereinafter phase 'operation have made it expedient to conmore fully described. v A

lsider and perfect a process employing vapor phase The present invention is concerned with the I operation in which a solid bed of catalyst, for 40 maintenance of the effective usefulness ofthe examplealuminum chloride impregnated or decatalyst mass over a longer period ottime than posited'upon suitable carriers, either reactive to has heretofore been possible.vv This may be ac-r some extent` or inert. is employed and in which complished by introducing eitherjint'e'rmittently.-

.the normal. parailln vapors together with procontinuously or continuously-intermittently, vamoter are allowed to pass through and in inti- 46 pors of aluminum chloride or other suitable mate contact with the bed under isomerizatio Friedel-Crafts type catalyst vinto the catalyst reaction conditions. mass which is catalyzing isomerisation reactions. The present invention is concerned with the This maybe accomplished'in a number ofways `vapor phase isomerization oi normal paraflins to he more fully hereinafter disclosed. It'has Econtaining at least four carbon atoms per mole- 'so been found, however, that. particularly with re- `culo or with the isomerization of branched chain spect to the carrier, the eectivc life 'is jlparailins to more highly branched chain paraf- -materially lengthened, .and from the'econoinics 'A The catalystemployedia prepared by imof the Yprocess a commercial plant may bemore 'regnating and sorbing aluminum chloridegor eiiiciently operated by employing the improve- 'r suitable Friedel-Crafts type catalyst on vor 65 ments herein described. 1 "f aisselle It is an object of the present invention to maintain a longer effective usefulness with incident high catalytic activity of an isomerization catalyst bed, particularly in connection with its use in the vapor phase lsomerization of normal parafflns of at least fourcarbon atoms per molecule to the corresponding isoparaiilns. Itis a further object of the present invention to carry out a continuous commercial process for the production of.; 1

high yields of isoparaiilnsy from their corresponding normal parafilns as economically as possible j and toavoid the necessity for shutdowns due to excessive degradation of the catalyst bed and/or plugging of valves and lines with aluminum chlo-` ride` deposited thereon and therein which. was

caused by the fact that excessive amounts of alu-l minum chloride were vaporized or'dissolved in the eilluent coming from the It is a further object of the invention to addA and substantially completely sorb aluminum chloride or other Friedel-Crafts type catalysts in vapor form to a catalyst bed to lengthen its ef'- fective catalyst life, and yet to add these vapors in such a wayfas to prevent substantial loss of aluminum chloride vfrom-said. bed through vaporization or solution in the reacted enluent isomerization reacV vapors and no further sorption thereof is .possible under the particular temperatures maintained. The temperatures employed may be those of the isomerization reaction or slightly lower or 50 F. to 100 F. higher than the highest temperature to be contemplatedfor use in the ,subsequent isomer-ization reaction zone. In general, a temperature of between about 200 F. and

400 F. is employed where normal pentane isom- I eirizations .are contemplated. In preparing a catalyst for use with normal butane isomerization, temperatures of from 250 F. to 450 F. are

generally desirable for the impregnation step. The amount of aluminum chloride contained in the pores of sorptive carriers varies depending upon ther particular sorptive carrier employed,

. gases at or above the sublimation temperaturesl but in generalit will be found to range between about 8% and about 20% by weight of the catalyst mass. The aluminum .chloride vapor carriers employed may be of widely varying characterlstics but it is only necessary that they be employed .for the aluminum chloride and that coming therefrom. It is a further object ofthe y invention to maintain a substantially uniform distribution of aluminum halides or other Frleas others which will hereinafter appear upon Aa fuller and more complete understanding of the invention, the following description and explanation of the novel process follows.

Dried aluminum chloride or other suitable Friedel-Crafts type catalyst is impregnated on and sorbed in the pores of a relatively highly porous carrier such a's,'for example. activated carbon, diatomaceous earth, acid-treated .clays such as. for example, Super Flltrol, the bentonitic clays, montmorillonite, bauxite, either partially or substantially completely dehydrated such as Porocel, activated" alumina, alumina gel, silica gel, and the like, and the mixture heated to an elevated temperahire, depmding-upon the particular carrier employed,sumcient to complete the sublimation of the less tenaciously held aluminum chloride, for example. followed by a removal ot all excess or extraneously and carriers.

- they'be relatively inert with regard to the alumi- .num chloride under the conditionsr employed for impregnation of the aluminum chlorideon porous Thus, for example, such gases asmtrogen; air, carbon dioxide, hydrogen, lchlorine, hydrogen chloride, methane, ethanegfpropane,

normal butane l or. isobut'ane and the like,may

be, either singly or in' admixture with one another, employed for this purpose.

One of the particularly desirable carriers which have been employed is known under the trade name of-Por'ocel and comprises a calcined bauxite. However, for best activity it is de'- sirable to dehydrate this calcined bauxite, or

any other carrier, to a point substantially below that where water is given off under the isomerization conditions to whichv the carrier subsequently is subjected. The bauxite may be dried and calclned by any of the customary methods employed. The particular calcined bauxite which is preferred in the present invention is Porocel which has been previously heated for a period of about 18 hours at a temperature between about 950 F. and about 1000 F. or 2-3 hours at.1300 F. As previously stated,lone of the methods of preparing the catalyst is simply to charge the isomerization reactorwith the dehydrated Porocel alone land to impregnate and sorb aluminum chloride directlytherein, or the Y loosely held aluminum chloride from the porous masa 'Ihe temperature under which this 'may be carried out is generally from 50 F. to 100 F.

in excess of the highest temperature to be employed inthe isomerization reaction in which thel catalyst mass will be employed.`

Still another method of preparing the cat- .alyst bed is to take a suitablehlghly sorbent carrier of the type Vheretofore specified andto independently sublime or vaporizeA aluminum chloride and by means of a suitable carrier gas or vapor, impregnate theporous carrier with the .aluminum chloride until such time and in such amounts so that the carrier is substantially completely saturated with *theal'uminum chloride Porocel' may be impregnated with anhydrous aluminum chloride in a separate and independent step and the resultant catalyst may be a charged to the isomerization vreaction zone.

The feed stock employed in conjunction with this catalystmay be any one of a number of common types of feed stocks found in petroleum refineries. useful comprise essentially normal butane, normal-pentane, normal hexane, normal heptane, 2-

'methyl pentane and higher homologues and/or mixtures of two or more of these normal paraiilns as well as such natural mixtures as field butanes,

ditibssi of normal., pentane and the above-t-mentioned casinghead gasoline and the like. `The lprocess nds its greatest utility,` however, in the use of feed stocks predominating in normal butane and/or normal pentane. The process is chiefly designed to convertr normal butane to isobutane althouglivby' slight alterations, oi' reaction cont'may be employed for the isomerization higher'liomologues thereof. .Particularly when The particular feed stocks which are v :masas emplylna the higher homologues it is'often desirable to 'employ molecular" or free hydrogen in ordertouppreixsasian-lispossiblethecracking '.tendencies.` Thehydrogennotonlyservesthis `chlulldc ito the ctlyt bed simultaneously with the isomerisation reaction.

The isomer-ization reaction is carriedout in the presence of suitable promoters, as heretofore mentioned. These are customarily employed in j amounts-ranging between about 1% and about 18%, although higher amounts may be employed without deleterious effects on the isomerization zreaction. oftentimes it is desirable to employ higher amounts of promoten'particularly where these promoters such as chlorine, hydrogen chloride and/or hydrogen, serve as -the carrier medium in introducing the further quantities of aluminum chloride into the catalyst mass :since by regulating the amount of carrier gas it is possible to regulate the amount of aluminum chlo-` ride being introduced into the catalyst bed.

Times of contact vary, particularly in continuous units, but in general the time of contact will be betweenabout 0.2 and about 3 liquid volumes of feed stock per volume of catalyst per hour (30 to 600 seconds) and the temperature maintained in the reaction sone will vary depending upon the particular feed stock charged, between about l50 F. and about 400* F., preferably between about 200 F. and about 325 F.. with a pressure being maintained between about atmospheric and-about 350'lbs./sq;` in. The adjustment of the pressureis usually determined by and confined to. that pressure which will most efficiently effect a separation of hydrogen chloride in the stripping tower to which the reacted product' is fed, although the pressure may be varied above or belowl such pressures if desired, particularly in cases where an efficient separation of hydrogen A the particular feed mixture being charged to the reaction zone. The isomerization of normal butane requires slightly more drastic conditions than does vthe isomerization of normal pentane which has been found to lhe somewhat more `susceptible, to cracking. but the use of elemental or molecular hydrogen in the case `of normal y pentane isomerization will permit theuse of slightly more drastic conditions because of the vtendency ofhydrogen to suppress the cracking of normal pentane and its isomer. For normal butane isomerization., temperatures between 250 Rand 350 P.' are generally employed; and for normal penta'ne isomerizatiom temperatures `of weight of aluminum chloride charged the cat- Aalystmass.-

n has' 'also' been' round expedient in om; out a commercial operation Aof this type, pumularly where ordinary refinery C4 and/or Cs feed stocks are employed,`to subject the feed stocks which are known to contain water and/or oleflns.

such as butenes. pentenes, orlowermolecular weight monooleiinato a pretreatment with` a suitable agent for ,the removal of water and/or oleiins if 'they are present in objectionable quantities. Suchva treatment may embody the use of concentrated sulfuric acid of the order of 98% or higher, or the use of chlorsulfonic or ucrsulfonic` acid for the same purpose. or variousother types ofv common expedients for removal of `oleiins. In cases where concentrated sulfuric acids areso employed, .it is preferable. in order to prevent any chemical degradation of aluminum chloride by contactwith small amounts of entrained sulfuric acid. to-pass the feed stock so'vtreated through a suitable lter nlled with a coagulating medium in order to condition theV feed for its subsequent isomerization treatment. Suchv substances should usually be substantially waterfr'ee and should be capable of adsorbing sulfuric acid readily. For example, activated charcoal,

clay or bauxite may be employed, as well as other 'substances commonly employed in such treatbetween 175 F. and 250 Fgare generally em- 'ployed. Furthermore, the temperature may be increased to some extent as 'the catalyst mass 'becomes degraded beyond a point where,V additional introduction of .aluminum chloride to the catalyst mass does not maintain its activity. .In 'such acase' the temperature is raisedand the reaction conditions are slightly more drasticfor a given feed stock in order to' attain the ments. This pretreatment is best carried out in liquid phase operation in which the feed stock is maintained in liquid state through the clay filter treatment. The clay illter treatment of course may be omitted if the amounts of ysulfuric `-acid present in thetreated feed stock are not sumclent to cause any appreciable disturbance' of the activity of the aluminum chloride in the subsequen isomerization reaction.

The feed stock is subjected to sumcient heating to vaporize the same under the pressures obtaining and its temperature is subsequently adjusted in accordance withk anumber of factors. In the ilrst place, the temperature is generallyadiusted to that desired to be maintained in the reaction zone. This may be accomplished in two ways. In the ,first method, the normal paraflin is heated to the desired reaction temperature and it is passed into a chamber containingv granular or comminuted aluminum chloride with such velocity as to vaporize and pickup the desired amount of aluminum chloride, and this aluminum chloride together with the normal paraffin vapor is introduced into the reaction zone. However. a second method is also contemplated in which only a portion of normal parailln vapors are carried through the aluminum chloride pick-up chamber, the remaining portion of the normal parafn vapors being bypassed directly to the'isomerization reaction zone with a cooling `or heating thereof in order to adjust the temperature tothev desired reaction temperature. Either of these two methods are preferred since-it has been found `that by operatingfin accordance with these steps the aluminum chloride. charge in pick-up drinn undergoes very little if any degradation to r tionresidesinadmixingaportionofthepro-A moter such as, Vifor example, hydrogen `chloride and/or chlorine and/or hydrogen with the normal param'n vapors and conducting `the mixture yield of desired product per unit of linwhole'orinparhasbefore, through the alunniamas-4s num chloride pick-up drum where the aluminum chloride vapors are carried by these gases .and

-vapors to the isomerization reaction zone for sorption in the catalyst mass under the isomerization reaction conditions. It has been found that once the isomerization catalyst mass has atroi! aluminum chloride based on the feed, preferthe amount should not exceed that which can be substantially completely sorbed. The upper limit,

l therefore, is really xed by the capacity of the sorbent carrier to take up the aluminum chloride vapors. It is generally not desirable to introduce aluminum chloride vapors in amounts over and abovethat which will be substantially completely sorbed. In general, the reacted vapors leaving .the isomerization zone shouldcontain not more than about 0.004% by weight, based on the hydrocarbon feed. of aluminum chloride since un- -der continuous opf'srating conditions higher amountsA represent unsorbed and loosely held aluminum chloride contained in the isomerization catalyst bed which tend to eventually lead to the difficulties heretofore mentioned such as line plugging, valve sticking, etc.

Still other variations of the method of introducing the aluminum chloride vapors into the isomerization catalyst bed are employed. The

promoter such as, for example, hydrogen chloride, `either alone or in conjunction ,with molecular hydrogen, may be used exclusively for picking up the aluminum chloride vapors and introducing them into the reactionl zone.

Preferably these promoters are introduced in the reaction zone alone or admixed with that portion of the normal paramns which does not go through the aluminum chloride pick-up chamber.

No special type of apparatus construction is necessary in carrying out the process of the present invention. It is suflicient that equipment whichy has customarilybeen employed ior vapor phase treatment of hydrocarbon with solid bed type catalyst will serve to accomplish satisfactorily the present process. Ordinarily, reactors containing supported plates or baskets for the deposition of catalyst masses and through which vapors are allowed to pass may serve as thereactors. Since the process may be carried out under superatmospheric pressure the vessels should be of the ordinary pressure type. The re actors may be a single reactor or a plurality of reactors arranged in series or parallel so that the feed stock and the unit may be continuously on-stream even thoughbne or more rebe cut off-stream and regenerated or replaced A, without interruption of the process. The reactors may also be Jacketed in order to-maintain their V temperature,` and convenient heat'interchangers may be employed, particularly with respect to the introduction of the reacted emuent into the pro- '.moter stripping tower and the removal oi the stripped reacted mixture therefrom.

Not only may the catalyst mass be maintained lso far as its activity is concerned in the manner 'heretofore described, but it may likewise'be prepared or regenerated in the same manner,` that is, by the use of normal butane alone, for ex- 1 ample, or with hydrogen chloride or chlorine vapors or with the chlorine-containing lvapors alone, as carrier media for vaporlzed aluminum chloride which is introduced to reimpregnate or impregnate the Porocel or other absorbent carrier employed. In regenerating the catalyst mass it is suggested to remove substantially all carbonaceous impurities contained in the pores thereof by combustion using air or free oxygen. either undiluted or diluted, with 'an inert ygas such as nitrogen, carbon dioxlde,letc., to burn the carbonaceous material from the pores. It is then possible to reimpregnate the pores of the carrier with aluminum chloride vapors as previously described.

In order to more fully understand the character of the invention, reference is had to the accompanying drawing which represents more or less diagrammatically in sectional elevation a `plant set-up designed to carry out the present invention.

vl'or purposes of illustration the process will be.

specifically confined to the treatment of a feed stock initially containing normal butane and traces of water and, oleilns. The catalyst employe'd will be granular, substantially anhydrous actors may be oE-stream for removal of spent catalyst or itsregeneration. It isy preferred in' the present operation to have more than one reactor and to havethe reactor vertical in shape and to introduce the feed stockat the bottom thereof and'allow it to flowthrough the catalystr Amass upwardly `'and emerge from the reactor from aluminum chloride; vand the carrier, substantially dehydrated vPorocel. A typical feed stock having a composition roughy of about 92% normal butane, 0.5% propane, 0.5% pentane, and containing 0.01% H2O and 0.1% of C4. oleilns, the remainder being isobutane, .was fed through line 2 by means of pump 3 and line 4 into a scrubbing tower 5 filled with Raschig rings, broken stoneware, glass and the like, through which concentrated sulfuric acid having a concentration between about 96% and 100%, preferably about 98%, was introduced into scrubbing tower 5 by means of lines 6, 8 and il controlled by valves l and 9, and conveyed to thescrubbing tower i by means of pump i0. The feed stock in Vthe liquid phase was withdrawn from scrubbing tower 5 through line l5 while the sulfuric acid was withdrawn from the tower through line l2 controlled by valve I4. This acid may be returned tothe scrubbing tower through lines I9, 8 and ll or it; may be withdrawn from the system through lines I9 and 6, valve 9 remaining closed, and may be utilized in a number of ways such as in the production of alcohols and esters through hydrolysis of the acid sulfates contained therein, or it may be sent to an allrylation unit where this acid containing the acid sulfates is subjected to alkylaftion inv the presence of isoparailins. The overhead fromv scrubbing toweri vis conducted through line l5 into a settling zone IB which vmay contain gravel or othercinert solid ma- `to thescrubbing tower by means of lines Il, il,

. 9 l and I I, the valves being suitably manipulated for the desired procedure. The normal butane substantially free of water and oleilns is then conducted by means of line 20 either to a filtering treatment in zone 25 or it may be conducted directly tothe isomerization unit through line 2l controlled by valve 22. Ii the material is subjected to a filtering treatment to removethe last 'traces of sulfuric acid it isf passed through line 23, controlled by valve 24, through the illter 25 and from therethrough line 2B, controlled by valve 21, into line 20, and `from there into heater 29 wherein the temperature of the normalbutanephase under the reaction conditions and so as to be capable of carrying the desired quantity of aluminum chloride vapors into the isomerization reactor. The temperature customarily -attained in this second heater is approximately 300 F. and the pressure about 250 lbs/sq. in. These vapors are then passed to the reactor through line ll byisomerization reaction zones and/or 8l byy passing through open valve M, line 4l, lines 40 and'll, controlled by valve 5l, and lines l! and I0, controlledby valve 59, in which case they go through a heater or cooler 48 which is designed to properly adjust the ilnal temperature of the normal butane going to the isomerization` reaction zones Il and/or Il. or 'these 'normal butane unes u and mand 41 and si. The temperature in the isomerization reaction zones 60 and 6I which are maintained as illustrated in the drawing in parallel'operation is about 300 F. and the pressure is about 250 lbs/sq. in. The amount of aluminum chloride leaving pick-up drums I1 and v il and entering reactors 60 and iii .is regulated lov thatit rst will replace the small amount of aluminum chloride which is vaporized from the sorptive carrier and is thus lost from the reactors,

and 'will also replace the aluminum chloride on the carrier' at least'as rapidly as this sorbed aluminimum chloride is degraded and loses its activity. However, .the amount of aluminum chloride added should not exceed that which'can be sorbed by and substantially retained by the carrier in the reactors. This amount of aluminum chloride to lbe added to the reactors is controlled either-by regulating the temperature under which 'the aluminum chloride drums are operated, or by controlling -the ilow of hydrocarbon and/or promoter vapors passingtlirough the aluminum chloride drums, or by controlling the amount and frequency'with which aluminum chloride is added to these aluminum-chloride drums.v

The operation `of aluminum chloride pick-up drumsv 31 and 4| is such that the amount of gases going #through the pick-up drums, together with the temperature under which the drums are maintained, together with the amount. of aluiriinum'chloride contained therein, is' such as toV maintain a substantially constant rate oi j ilow'particularly in a continuous operation of vapors'lnay be split, a portion of them' going' through' aluminum chloride pick-up.drums 31 and/or Il vand the remaining portion thereof goingthrough line as previously described.

Hydrogen chloride, or 'chlorine and/o'r elemental or free hydrogen is introduced into the system through line 11, controlled by -vaive 18,' and is introduced into the'isomerization zone by the following alternative methods: From llne 1l lt is conducted to line 80, controlled by 'valve l i where 'it is admixed with the normal butane' vapors coming from the rst heater and is subjectedto the' iustmen't. Or the promoter maygo through line i al, controlled by valve i5. and pass through aluminum chloride pick-up drum' 4I, orit may go, withvalves $3 and 55 closed, through line I6,

' controlled by 'valve 51, into aluminum chloride pick-up drum 31, in which-case the promoters the un'it, so that the activity of the catalyst mass in reactors and Il' is maintained at a uniformly high level 'within practical limits. The variation in the operation of pick-up chambers or'drums 31 and 4| 'permits of the control of v'various factors all directed to the ultimate amount of aluminum chloride going to the catalyst The temperature on the pick-up chambers or drums may be varied somewhat from the'300" F. indicated. The amount of'feed stock and/or promoter passing through the pick-up drums may be vvaried to give the desired amount o f aluminum chloride. 'In other words, the normal butane vapors or the promoter' vapors and the pick-up'drum may be controlledby intermittently removing large amounts or continuously I lremoving small and controlled amounts.

serve 'as gaseous media for theintroduction o! the aluminum-chloride vapors into the Lsomeriaation reactionzone'. The gases' and vapors'l coming from pick-up drums `31 and 4i are charged to isomerization reaction zonesfll and 8l through Asheretoiore stated, the catalyst mass or`- bed maintained in the reactors 60 and 6I is sorbed aluminum chloride on lPorocel which has been substantially -completely dehydrated. The normai butan'e and promoter passing-through at the rateo! about 1,`v./v./hr. is passed through upwardly and discharged through line 62, -controlled by valve il, and/or line 83, controlled by valve J0l, andthe eilluent coming through line Il is cooled by means of cooler 61' and passed through-a surge drum I maintained at a temperatureofabo'ut 160 F. and a pressurel of 240 lbs/sq. in. `where the reactor product is condensed and temporarily stored to provide a steady feed to the stripper y14. Any sludge or heavy degradation' products formed and present in the reactor eiliuent entering the drum 68. may be .eine

11 settled to the bottom of the drum and withdrawn through line 69, controlled by valve 10. The paramnic reacted mixture together with promoter is then passedthrough line 1| by means of pump l2 through a heater 19 and introduced `into stripper 14 containing Raschig rings or plates (not shown) by means of line 1 I. Stripper 14 is maintained at a temperature of about 155 F. at the top and about 240 F. at the bottom andisunder a pressure of between about 300 and about 350 Iba/sq. in. This facilitates the removal of hydrogen chloride and/or hydrogen. and chlorine overhead through line 15, controlled by valve v19, and itmay be either withdrawn from 'the system in whole or in part through line 11, controlled by valve 18, or recycled to the isomerization unit through line 19 as heretofore described. Fresh promoter in the desired amount may likewise be added through 11 controlled by valve 1.8. The strippedreaction mixture is conducted from stripperl 14 through line 83 into cooler 84 'and from thence into mixer 88 where it is intimately admixed with caustic soda solution introduced into the the hydrocarbons passing from the mixer 85 through line 48 into settler 81, the caustic being removed through line 88, controlled by valve 89. This caustic may either be returned to the mixer for the treating of further quantities of stripped duced linto still 99 equipped with a heating coilr 99a where a separation between isobutane and normal butane is eected, the isobutane coming oil overhead through line |00, controlled by valve |03, `and unreacted normal butane is withdrawn from the bottom through line lill, controlled by valve |02, and is either withdrawn from the system by means not shown or recycled to the isomerization unit by means of line llllbackrto feed line 2 where it is sent to the sulfuric acid scrubbing system to remove any water. which may have been formed during its treatment in the system or which may have been taken up in the caustic treatment in mixer 88.

'I'he isobutane then may be employed in an alkylation unit or it may be employed in any cally desired that the invention be not'elimited thereto.

Ylturample 1 an isomer-ization catalyst was prepared by charging to the reactor about 1.5 lbs. of anhydrous aluminum chloride and by placing there'- over about 11 lbs. of low iron content, substantiallycompletely dehydrated Porocel which had previously been subjected to'a temperature of about 1000. F. `for about 24 hours. The charge waswpiQlfien maintained at atmospheric pressure mperatureof between about 250- F. and

12 325 F. while introducing normal butane vapors for about 24 hours through the -bottom of the reactor. A fter this treatment and up to about the first 200 hours 6 weight percent hydrogen chloride was admixed with the n-butane charged and the temperature was gradually raised from the initial 250 F. up to about 350 After 200 hours lunder these conditions, the feed mixture of normal butane and hydrogen chloride in the same percentages was passed at a rate of about 1 liquid volume of feed per volume of catalyst space per hour through anhydrous granular aluminum chloride in a separatechamb'er at a temperature of about 230250 F., and the re,- sulting mixture of normal butane. hydrogen chloride 'and aluminum chloride vapors was passed through the catalyst contact bed at the rate heretofore described while the temperature of the reactor was maintained at about 350 F. Under these conditions the yield of isobutane averaged about 50% by volume even after about the one-hundredth hour of operation in this manner. The temperature of the reactor was then reduced to about 300 F.. said temperaturebeing maintained at 'this point through the remainder of the run. The higher temperature .was maintained in an e'ort to determine the amount of aluminum chloride vapors which were coming overhead and which represented aluminum chloride not tenaciously held in the catalyst mass. It was found, however, that only about 0.001% to about' 0.004% lby weight of the feed represented aluminum chloride leaving the reactor. The yield of isobutane when the reactor was maintained at about 300 F. was found to average about 40% by volume based on the liquid hydrocarbon fed.

From time to time additional charges of anhydrous, granular aluminum chloride were added to the pick-up dru'm through which the normal butane-hydrogen chloride mixture was passed prior to its introducttion into the reactor. AThe weight per cent of aluminum chloride based on theliquid normal butane fed and added to the reactor varied somewhat depending upon the quantity of aluminum chloride present in the pick-up drum, and ranged between about 0.002% and about 0.15%, the average sbeing about 0.01%. At no time, however, did the amount of aluminum chloride contained in the emuent rise above 0.004% by weight of the feed. After about 800 hours the run was discontinued, although the catalyst mass was by no means spent so far as its isomerization activity was concerned.

The aluminum chloride pick-up should be maintained at a. temperature above about 185 F., preferably between about 230 F. and the isomerization reactor temperature.

As illustrative of an experiment wherein among i Example 2 An isomerization catalyst was prepared by charging to the reactor about 1.15 lbs. of anhydrous aluminum chloride and by placing thereover about 11 lbs. of low iron content, substantially completely dehydrated Porocel (less than about 24 hours at a temperature of about 300` F.

13 and under superatmospheric pressure. The catalyst composition then amounted to about 12 weight per cent oi.' aluminum chloride and about 88 weightper cent of the dehydrated Porocel and all of the aluminum chloridewas substantially tenaciously held in the pores of the Porocel.

A feed stock comprising about 93.1 volume per cent of normal butane, about 6.6 volume Vper cent of isobutane and about 0.3 volume per cent oi Cs and heavier-.paraiilns was fed ata rate of between about 0.92 and about 1.06 liquid volumes of normal butane vaporized feed per volume oi catalyst per hour upwardly through the catalyst bed with about 6 weight per cent oi' hydrogen chloride in a separate stream to a reactor. The pressure on the isomerization reactor was maintained Vat about 200 lbs./sq.'in. `and the run was carried out for a total number ofhours of 663. During the iirst few hundred hours of the run the reactor temperature was raised gradually from about 250 F. to about 300 F. so as to maintain approximately a 40% conversion or yield of isobutane. The aluminum chloride addition was startedas soon as the activity appeared to be dropping ofi when the reactor temperature was maintained at about 300 F. The aluminum chloride was added by a number of methods. While the reactor temperature was maintained at about 303 F., from the one hundred twenty-second to the one hundred sixty-third hour of operation a pickup drum of aluminum chloride was inserted into the hydrogen chloride stream, this drum containing lumps of anhydrous aluminum chloride. The drum temperature was maintained between about 300l F. and about 250 F. and its actual use on stream amounted to about a total oi 42 hours. The vapor carrier for the aluminum chloride was the hydrogen chloride promoter, which was removed -Vfromthe nal product and returned to the isomerization reactionl zone through the aluminum chloride drum. During this operation the activity and conversion dropped `from 40% to about of isobutane based on the normal butane fed. `In the subsequent operation, from the one hundred seventy-sixth to the two hundred seventy-eighth hour, where the aluminum chloride pick-up drum was maintained at a temperaof aluminum chloride and all oi' this aluminum l chloride was substantially tenaciously held in thc ture of about 240 F. with a reactor temperature v varying from a low of about 250 F. up to a high -of 303 F. and the fresh-charge of. aluminum minum chloride was placed in the pick-up drum f and it was used for a total of 266 hours with the .drum temperature being at from 220 F. to 240 F. yand the reactor temperaturebeing maintained at about 303 F. Here the carrier employed lor ythe laluminum chloride pick-up was only .the normal butane ieed stock to the exclusion of hydrogen chloride, and surprisingly not only did the conversion increase to between 48 vand 52 volume per cent under the same conditions but in addition the conversion was much more consistent lpressure with normal butane vapors. Y catalyst composition was about 88.1 weight per chloride necessay to maintain thev catalyst activity until .the total run of 663 hours was completed. The residual aluminum chloride in the pick-up drum which was not discharged into the catalyst mass was in excellent condition for further use inthe reaction and did not contain any black non-volatile liquid residue such as had been found where the hydrogen chloride or mixtures of hydrogen chloride and normal paramn were employed as the carrier vapors. After the six hundred-sixty-third hour oi operation the run was discontinued because of shut-down over a period oi' holidays and was not renewed although 'the catalystmass was 'still very active at the end Example 3 A further experiment was conducted in much the same manner as described with reference to Example 2 but the'aluminum chloride vapors which were introduced during the run were in'- troduced by means of normal butane exclusively.

An isomerization catalyst mass was prepared by charging the reactor with a substantially completely dehydrated Porocel having a low iron content in the amount of about 11 lbs. and placing immediately thereover in the isomerization reactor about 1.15 lbs. of anhydrous granular aluminum chloride. This catalyst mixture was` then pretreated for about 24 hours ata temperature of about 325F. under superatmospheric 'Ihe final cent of.Porocel and about 11.9 weight per cent pores o1' the Porocel carrier.

` vFor about the iirst 528 hours of operation of this catalyst mass the reaction conditions were maintained substantially constant at about 200 lbs./sq. in. pressure and at about 300 F. with a normal butane throughput of about 1 liquid volurne of` normal butane per volume of catalyst' mass per hour, using about 6% by weight of hydrogen chloride promoter. Of course during such an-extended period of operation `slight variations in these reaction conditions occurred but in general the conditions were maintained as stated. Beginning with about the five hundred twentyninth hour the amount of hydrogen chloride promoter employed lwas dropped to and maintained at about 3% but it was found upon subsequent dropping of this amount of hydrogen chloride that there was a decided drop in activity a'nd the hydrogen chloride concentration was brought up to between about 3% and 4% inl order to maintain a 45% conversion and which was maintained up to almost 700hours of total operation of the catalyst mass. f

The feed stock employed was substantially the same as that described in Example 2 and the aluminum chloride charged to the pick-up drum through which the-butane` vapors werewfed 4was charged in increments of lb., 0.13 1b..,0.3 lb... 0.3

l lb.`and 0.5 lb. In general, these drums were left on stream until such time as they no longer contained appreciable amounts of aluminum chloride, and this amounted to total hours of contact of roughly from 164 up to 192 hours except in the case of one drum which was on stream at a time f when the unit had the feed cut of!V in order to improve the mechanical operation `oi! the unit.

In no case was there any black degradation residual liquid in the aluminum chloride pick-up vdrums` when they were taken oil stream but a alyst mass in order to maintain a substantially constant conversion of .l normal butane to isobutane. 300 F.

'I'he yield of isobutane varied between about and about 50 volume per cent based on the normal lbutane fed, and the selectivity of the` normal butane reacted and which went to isobutane varied between about 90% and 98%. It was found, surprisingly, thatv when normal butane was exclusively employed as the carrier medium for the aluminum chloride vapors entering the catalyst bed that the catalyst life increased to a point far beyond that heretofore known. `.lifter a total of 528 hours of operation,

138 gallons of isobutane were produced per pound of aluminum-chloride charged. This aluminum chloride includedl the aluminum chloride originally in the catalyst bed as well as the aluminum chloride employed throughout the experiment in the pick-up drum andv which was introdnuced into the catalyst bed during the experiment. This is indeed a remarkable life of the aluminum chloride when considered in conjunction with the length ofthe run and has heretofore not been obtained so far as known.

Having thus fully described and illustrated the character of the invention, what is desired to be secured by Letters Patent is:

1. In a process of isomerizlng normal parafdn containing at least four carbon atoms per molecule in the vapor phase by contacting the same underY isomerization reaction conditions and in the presence oi' promotional amounts of hydrogen chloride with a catalyst mass comprising essentially a porous carrier dehydrated to a water content of less 'than 2% incapable of releasing any substantial amounts of free water under the isomerization reaction conditions. and containing sorbed aluminum chloride, the improvements comprising adding', at least intermittently during the isomerization process, ra gasiform carrier containing aluminum chloride vapors and substantially free of halogen-containing promoters and comprising essentially only normal parailin vapors, to the aluminum chloride catalyst mass to maintain and -prolong the onstream isomerization activity of the catalyst mass, limiting the amount of aluminum chloride vapors so added below that required to exceed the saturation point of the porous carrier under the prevailing isomerization reaction conditions whereby the efiluent vapors from the isomerization reaction zone are substantially free of aluminum chloride. 2. A process asin claim l wherein the gasiform carrier is at least a portion of the isomerization feed stock.

3. In a process of isomerizing normal parailin It varied from about 220 F. up to containing at least four carbon atoms per mole-l cule in the vapor phase by contacting the same under isomerization reaction conditions and in the presence oi' promotional amountsof hydrogenchloride with a catalyst mass comprising porous alumina dehydrated to a water content of less than 2% incapable of releasing any substantial amounts of free water under the isomerization reaction conditions, and. containing sorbed aluminum chloride. the improvements g comprising adding. at least intermittently during the isomerization process, a gasiform carrier containing aluminum chloride vapors and substantially free of hydrogen chloride and comprising essentially only vapors of normal paraiiln containing at least four carbon atoms per molev cule, to the aluminum chloride catalyst mass 'to maintain and prolong the "on-stream isomerization activity of the catalyst mass, limiting the amount of aluminum chloride vapors so added below that required to exceed the saturation point of the alumina carrier under the prevailing isomerization reaction conditions whereby the eiiluent vapors i'rom the isomerization reaction zone are substantially free of aluminum chloride.

4. A process ss in claim 3 wherein the gasiform carrier is at least a portion of the isomerization feed stock.

5. In a process of isomerizing normal paraiiin containing at least four carbon Vatoms per molecule in the vapor phase byv contacting the same under isomerization reaction conditions and in the presence of promotional amounts of hydrothan 2% incapable of releasing any substantialV amounts of free water under the isomerization reaction conditions and containing sorbed aluminum chloride, the improvements comprising adding. at least intermittently during the isomerization process, a gasiform carrier containing aluminum chloride vapors and substantially free of hydrogen chloride and comprising essentially only normal parailin vapors. to the aluminum chloride catalyst mass, and thus maintaining the amount of aluminum chloride sorbed in the bauxite between about`8 and about 20 weight per cent of the catalyst mass.

6. A process as in claim 5 wherein the gasiform carrier is at least a portion of the isomerization feed stock.

7. In a process of isomerizing normal butane in the vapor phase by contacting the same under isomerization reaction conditions, and in the presence of promotional amounts of hydrogen chloride, with a catalyst mass comprising V bauxite dehydrated to a water content of less than 2% incapable of releasing any substantial amounts of free water under the isomerization reaction conditions and containing sorbed aluminum chloride. the improvements comprising adding, at least intermittently during t-he isom from normal butane in thel vapor phase under isomerization reaction 'conditions in the presence of hydrogen chloride and a catalyst mass comprising essentially aluminum chloride sorbed on a porous alumina carrier dehydrated to a water tion reaction conditions, the improvements comprising at least intermittently'during the isomerization process introducing small amounts of alu' minum chloride vapors into the said catalyst mass mixed with a carrier vapor therefor substantially free from hydrogen chloride andi comprising essentially only normal butane, in which suiiicient aluminum chloride vapors are thus introduced into the catalyst mass to maintain its isomerization activity but not to exceed substantiallyv complete saturationof the porous alumina under the reaction conditions maintained whereby the sorbed aluminum chloride is tenaciously held therein under the isomerization conditions maintained.

9. A process as in claim 8 in ywhich normal pentane replaces normal butane.

10. In a process of isomerizing normal parafilns containing at least four carbon atoms per molecule in the vapor phase under isomerization reaction conditions while in contact with a hydrogen halide and a bed of aluminum chloride tenaciously sorbed in a bauxite dehydrated to a water content of less than 2%, the improvement comprising extending the length of onstream operation of the catalyst mass by simultaneously passing at least one paraffin hydrocarbon in vapor phase prior to entering the isomerization reaction zone and in substantial absence of any promotor for the isomerization reaction through a pickup zone containing extraneous aluminum and in the presenceof promotional amounts of` hydrogen chloride 'yith a' catalyst mass oomprising essentially a carrier dehydrated to a water content of less than 2% incapable of releasing any substantial amounts of free water under theisomerization reaction conditions and containing sorbed aluminum chloride, the improvements comprising adding. at least intermittentlyV from the isomerization reaction zone are substantially free of aluminum chloride.

13. 4 process as in claim 12 wherein a carrier gas is employed to gas strip from the aluminum chloride porous carrier catalyst mass all but the tenaciously held aluminum chloride prior to employing the catalyst mass as an isomerization catalyst.

14. A process as in claim 12 wherein a carrier gas comprising at least a portion of the feed stock to the isomerization reaction is emf v ride porous carrier catalyst mass all but the chloride, passing the resultant gasiform mixture reference to the said dehydrated bauxite under the isomerization reaction lconditions whereby the aluminum chloride is substantially completely sorbed and tenaciously held in the said bauxite during the isomerization reaction.

11. In a process of isomerizing normal parafilns containing at least four carbon atoms per molecule in the vapor phase under isomerization Y reaction conditions while in contact with a hydrogen halide'and a bed of aluminum chloride tenaciously sorbed in a bauxite dehydrated to a water content equivalent to that obtained by heating the bauxite until the water content is reduced below 2%, the improvement comprising extending the length of onstream operation of the catalyst mass by simultaneously passing at least one paraffin hydrocarbon in vapor phase priorto entering the isomerization reaction zone and in substantial absence of any promoter for the isomerization reaction through a pickup zone containing extraneous aluminum chloride, passing the resultant gasiform mixture containing aluminum chloride vapors 4into the4 catalyst bed, maintaining the concentration of aluminumchloride sorbed on the partially dehydrated bauxite below its saturation point with referenceI to the said dehydrated bauxite under the isomerization reaction conditions whereby the aluminum chloride is substantially completely sorbed and tenaciously held in the said bauxite during the isomerization reaction.

12. In a process oi.' isomerizing normal parafiin containing at least four carbon atoms per molecule in the vapor phase by contacting the same under isomerization. reaction conditions tenaciously held aluminum chloride prior to employing the catalyst mass as an isomerization catalyst.

l5. A process as in claim 12 wherein a carrier gas comprising an inert permanent gas is employed for adding aluminum chloride vapors to the catalyst mass and the same carrier gas is employed to gas strip from the aluminum chloride porous carrier catalyst mass all but the tenaciously held aluminum chloride prior to employing the catalyst mass as an isomerization catalyst.

16. In a process of'isomerizing normal parafiin containing at least four carbonatoms per molecule in the vapor phase by contacting the same under isomerization reaction conditions and in the presence of promotional amount of hydrogen chloride with a catalystmass comprising essentially a carrier dehydrated to a water content of less than 2% incapable of releasing any substantial `amounts of free water under the isomerization reactionconditions and containing sorbed aluminum chloride, the improvements comprising forming the catalyst mass by adding aluminum chloride vapors, mixed with a substantially inert carrier gas, to the said porous carrier,

maintaining the concentration of aluminum chloride sorbed on the said porous carrier below itssaturation point with reference to said porous carrier under the yisomerization reaction conditions by stripping the catalyst mass with the inert carrier gas while substantially undersaid conditions until substantially no aluminum chloride vapors are present inthe oi! gases, employ- 18. A process as in claim 16 wherein the carrier gas comprises hydrogen chloride.

19. In a process of isomerizing normal paraffin containing at least four carbon atoms per molecule in the vapor phase by contacting the same underisomerization reaction conditions and in the presence of promotional amounts of hydrogen chloride with a catalyst mass comprising essentially a carrier dehydrated to a water content of less'qthan 2% incapable of releasing any substantial amounts of free water under the isomerization reaction conditions and containing sorbed aluminum chloride, the improvements comprising adding, at least intermittently during the isomerization process, aluminum chloride vapors mixed with an inert carrier gas to the aluminum chloride catalyst mass to maintain and prolong. the on-stream isomerization activity oi' theV catalyst mass, limiting the amount of aluminum chloride vapors so added below :that required to exceed the saturation point of the porous valumina carrier under the prevailing isomerization reaction `conditions whereby the eiiluent vapors from the isomerization reaction zone are substantially free oi' aluminum chloride. i

20. A process as in claim 19 wherein a car l rier gas is employed to gas strip from the aluminum chloride .porous alumina carrier catalyst mass all but the tenaciously held aluminum chloride prior to employing the catalyst mass as an isomerization catalyst.

I 21. A process as in claim 19 wherein a carrier gas comprising at least a portion oi' the paraiiin reed stock to the isomerization reaction is employed for adding aluminum chloride vapors to the catalyst mass and the same carrier gas is employed to gas strip from the aluminum chloride porous yalumina carrier catalyst mass all but the tenaciously held aluminum chloride prior to employing the catalyst mass as an isomerization catalyst. l

22. In a process of isomerlzing normal paraffin containing at least four carbon atoms per `molecule in the vapor phase by contacting the,

same under isomerization reaction conditions and in the presence of promotional amounts of hydrogen chloride with a catalyst mass comprising essentially a vbauxite dehydrated to a water content of less than 2 incapable of releasing any substantial amounts of free water under the isomerization reaction conditions and gas is employed to gas strip from the aluminum chloride bauxite carrier catalyst mass all but the tenaciously held aluminum chloride prior to employing the catalyst mass as an isomerization catalyst.

24. A process as in claim 22 wherein a carrier gas comprising at least a portion of the paraffin feed stock to the isomerization reaction is employed for adding aluminum chloride vapors to the catalyst mass and the same carrier gas is employed to gas strip from the aluminum chloride bauxite carrier catalyst mass all but the tenaciously held aluminum chlorideprior to employing the catalyst mass as an isomerization catalyst. 25. In a process of isomerizing normal butane to produce isobutane in the vapor phase by contacting the same under isomerization reaction conditions and in the presence of promotional l mass comprising essentially a bauxite dehydrated to a water' content of less than 2% incapable of releasing any substantial amounts of free water under the isomerization reaction conditions and containing sorbed aluminum chloride, the improvements comprising adding, at least intermittently during the isomerization process, aluminum chloride vapors mixed with an inert carrier gas to the aluminum chloride catalyst mass to maintain the amount of aluminum chloride sorbed in the said bauxite Ibetween about 8 and about 20 weight per cent o! the catalyst mass.

26. A process as in claim 25 wherein a carrier gas is employed to gas strip from the aluminum chloride bauxite carrier catalyst mass all but the tenaciously held aluminum chloride prior to employing the catalyst mass as an isomerization catalyst.

27. A process as in claim 25 wherein a carrier gas comprising at least a portion oi the parafn under isomerization reaction conditions in the l presence of promotional amounts of hydrogen chloride with a catalyst mass comprising essentially a bauxite dehydrated to a. water content of less`than,2% incapable of releasing any substantlal amounts of free water under the isomerization reaction conditions and containing betweenl about 8 and about 20 weight per cent of 5 aluminum chloride sorbed therein, the improvements comprising forming the catalyst mass by adding aluminum chloride vapors, at a temperature above 185 F. but below the temperature maintained in the isomerization reaction zone. to the said porous carrier, maintaining the concentration oi aluminum chloride within the abovestated limits and under the isomerization reaction conditions tenaciously held by stripping the catalyst mass with an inert gasiform carrier while substantially under the said conditions until substantially no aluminum chloride vapors are present -in the off gases, employing the mass as the isomerization catalyst mass and subsequently adding aluminum chloride vapors mixed`with an inert carrier gas to the catalyst mass at least intermittently during the on-stream" isomerization reaction to maintain the 4above-stated amounts of tenaciously held aluminum chloride.

29. A process as in claim 28 wherein the carrier gas comprises at least`a portion of the paraiin feed stock.

30. A process as in claim 28 wherein the carrierl gas comprises hydrogen chloride.

NORVAL F. MYERS.

(References on following page) amounts of hydrogen chloride with a catalyst.

REFERENCES CITED The following references are of record in the :me of this patent: 5

UNITED STATESPAI'ENTS Number Name Date 2,277,022 McMillan et al Mar.- 17, 1942 2,254,618 Y McMillan. et al Sept. 2, 1941 10 2,274,624 McMillan Feb. 24, 1942 2,281,924 de Simo et al May 5, 1942 Alexander June 14, 1921 22 Name Date de Simo et a1. Mar. 24, 1942 Downs June 11, 1929 Chenicek et al. Nov. 10, 1942 Danforth Feb. 22, 1944 Thomas Jan. 26, 1943 Danforth Feb. 22, 1944 Watson Mar. 16, 1943 McMillan July 6, 1943 Thomas Feb..23, 1943 Thomas et al Feb. 23, 1943 

